Epworth sleepiness scale (ESS)

The Epworth Sleepiness Scale (ESS) is a scale intended to measure daytime sleepiness that is measured by use of a very short questionnaire. This can be helpful in diagnosing sleep disorders. It was introduced in 1991 by Dr Murray Johns of Epworth Hospital in Melbourne, Australia.

The questionnaire

The questionnaire asks the subject to rate his or her probability of falling asleep on a scale of increasing probability from 0 to 3 for eight different situations. The scores for the eight questions are added together to obtain a single number. A number in the 0–9 range is considered to be normal while a number in the 10–24 range indicates that expert medical advice should be sought.

Calibration

The Epworth sleepiness scale has been validated primarily in obstructive sleep apnea. It is used to measure excessive daytime sleepiness and is repeated after the administration of treatment (e.g., CPAP) to document improvement of symptoms.